Medetomidine of formula 1

is a potent, selective α2-receptor agonist, used as an antihypertensive agent and as a sedative and analgesic for veterinary and human use.
EP 300 652 discloses that the S-enantiomer of Medetomidine, namely Dex-Medetomidine, possesses an enhanced α2-selectivity and potency when compared with the racemic mixture.
EP 300 652 also discloses a resolution method to separate the racemic Medetomidine in its single enantiomers. According to EP 300 652, the racemate is converted into a mixture of diastereoisomer salts which are then separated by repeated crystallisations.
The separation of the enantiomers is illustrated in an example, in which after several repeated crystallisations, a total yield of less than 30% is obtained.
Considering that such a process is time consuming and hence not suitable for an efficient industrial application, it would be desirable to find a more practical and efficient process to produce the target enantiomers with high optical purity and in high yield.